Hillary Clinton has been discharged from hospital after four days of treatment for a blood clot between her brain and skull.

The US Secretary of State was admitted to a New York hospital on Sunday and treated with blood thinners to dissolve the clot in the vein behind the right ear.

Doctors found the clot during a follow-up exam after she suffered concussion in early December.

Mrs Clinton's doctors say there was no neurological damage and that she is expected to make a full recovery.

Her spokeswoman said she had been "quite active" on the phone on Wednesday with aides and reviewing paperwork while she continued her recovery.

Mrs Clinton has been working from home since returning from her last foreign trip on December 7.

Her lengthy absence from the public eye had sparked claims from critics she is trying to avoid testifying in a congressional investigation into a deadly attack on a US mission in Libya.

Image:A smiling Hillary Clinton is driven away from the hospital

Earlier this month, the State Department said Mrs Clinton had contracted a bad stomach virus during her five-day trip to Europe. She had to cancel planned visits to North Africa and Abu Dhabi due to the illness.

A week later, Mrs Clinton's doctors said she had become severely dehydrated due to the effects of the stomach bug and had fainted, suffering a concussion.

They recommended she rest at home and avoid the high-intensity travel she had been accustomed to taking for her job.

Mrs Clinton has flown almost a million miles since taking office four years ago, visited 112 countries and spent some 400 days in a plane.

Her health kept her from giving evidence on December 20 about the attack on the US diplomatic post in the eastern Libyan city of Benghazi on September 11.

The assault, in which the US ambassador and three other American officials were killed, sparked a political storm in the US.

Republicans criticised Mrs Clinton's absence from the hearings, calling on her to testify in January.

Mrs Clinton, who is due to step down from her post in early 2013, was also absent from the White House last week when President Barack Obama named her replacement, veteran Senator John Kerry.